Open Stack

Hey all,

Our nova patch for networking[0] got stuck for a bit, because Nova needs
to know which network interface is in use for the node, in order to
properly set up the port.

The code landed for network_interface follows the following order for
what is actually used for the node:
1) node.network_interface, if that is None:
2) CONF.default_network_interface, if that isNone:
3) flat, if using neutron DHCP
4) noop, if not using neutron DHCP

The API will return None for node.network_interface in the API (GET
/v1/nodes/uuid). This won't work for Nova, because Nova can't know what
CONF.default_network_interface is.

I propose that if a network_interface is not sent in the node-create
call, we write whatever the current default is, so that it is always set
and not using an implicit value that could change.

For nodes that exist before the upgrade, we do a database migration to
set network_interface to CONF.default_network_interface (or if that's
None, set to flat/noop depending on the DHCP provider).

An alternative is to keep the existing behavior, but have the API return
whatever interface is actually being used. This keeps the implicit
behavior (which I don't think is good), and also doesn't provide a way
to find out from the API if the interface is actually set, or if it's
using the configurable default.

I'm going to go ahead and execute on that plan now, do speak up if you
have major objections to it.

// jim

[0] https://review.openstack.org/#/c/297895/